Hi, Need to upgrade my standard Chorus headunit (its just a radio/cassette player) to something higher up in the Audi range. Which headunits will fit and be a direct replacement? Don't really want to remove the cage, just want to remove the old unit and fit the higher spec one with CD straight away. I assume I will not need any adaptor loom or adaptor plates, just the replacement headunit and plug it all in. Can anyone advise me?